Service Manual
75
Service Procedure V:
Blower Testing and Replacement
Does the blower energize?
Ensure control display shows
“Heating.” Raise temperature
setpoint if necessary.
Is there 120 VAC across
the white and black
wires at location P3 on
the control board?
Refer to ignition
module/control board
illustration. Is there
120 VAC between
P7(5) and P7(3)?
Replace ignition
module/control
board.
Is there 120 VAC across
the white and black
wires at location P2 the
transformer?
Determine the power
source problem and
correct.
Check amp draw through
black wire lead from the
control board to the blower.
Is there 0.6 to 3.0 amps?
Is the blower
wheel secured
to the blower
motor shaft?
Call
Technical
Support.
Refer to ignition
module/control board
illustration. Is there 120 VAC
between P7(5) and P7(3)?
Replace blower (see Blower
Replacement Procedure, pg 76).
Is the blocked vent
switch in the normal
closed position?
Call
Technical
Support.
Is there 120 VAC across
the white and black
wires at the blower?
Replace the
blower (see
Blower
Replacement
Procedure,
pg 76).
Repair/replace
wire harness.
Black wire leading to blower
looped through amp probe
N
N
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
75